Drawn containers



Feb. 6, 1968 R. D. LURIE 3,367,554

DRAWN CONTAINERS Original Fild Dec. 17, 1965 INVEENTOR RANDOLPH D. LURIEgTTORNEYS United States Patent O 3,367,554 DRAWN CONTAINERS Randolph D.Lurie, Park Forest, 11]., assignor to Continental Can Company, Inc., NewYork, N.Y., a corporation of New York Original application Dec. 17,1963, Ser. No. 331,249, new Patent No. 3,231,937, dated Feb. 1, 1966.Divided and this application Sept. 7, 1365, Ser. No. 485,443

14 Claims. (Cl. 229-25) ABSTRACT OF THE DHSCLUSURE A drawn plasticarticle having a cup-shaped body with means forming integral portions inan interior peripheral surface for preventing the necking down of thebody during the drawing thereof. The integral portions are a pluralityof ribs extending from an upper edge and gradually merging into a smoothcontinuous unbroken surface adjacent a bottom wall. The ribs range inheight upwardly from about .005 in., and in number between to 110 foreach inch of periphery of the body Wall.

This application constitutes a divisional application of my copendingcommonly assigned application for US. Letters Patent, Ser. No. 331,249,tiled Dec. 17, 1963, and now Patent No. 3,231,937.

This invention relates to a novel plastic article, and in particular, toa novel cold drawn plastic cup-shaped body having means forming integralportions of an interior peripheral surface of the body which prevent thebody from necking or thinning during the formation thereof by a drawingoperation.

Independent of the final shape or contour of a drawn or redrawn plasticarticle, such as a container, by a convention-al deep drawing process,the container tends to neck down or thin in a peripheral area of thecontainer body adjacent the juncture of the body and bottom wallsthereof. This necking or thinning of the material adjacent the bottomwall can occur during any one of several drawing operations, but is mostprevalent during the second or redrawing operation. As a result of theformation of this conventional neck of thin material, one of threethings may happen to the redrawn container.

First, the material of the container may strain harden enough to cause abrittle break in the material. This may easily cause the bottom wall ofthe container body to be punched out during the redrawing operation. Ifthe break in the material is minute and remains undetected a perishableproduct packaged in the container could spoil or the shelf-life thereofcould be materially lessened due to atmosphere entering the containerthrough the break in effecting the product.

Secondly, the neck of thin material may propagate further along thecontainer body or wall and/ or the bottom wall of the container, thusrendering the container commercially useless due to the differentialwall thickness.

Finally, the material of the container may strain harden in this neckregion but the tensile forces may be too weak to tear the material thusforming an objectionable thin but relatively strong and highly orientedband around the container body.

In accordance with this invention, it has been found that the elongationto yield (the additional length to which a ductile plastic material maybe stretched before the onset of unstable viscous or plastic flow) of atensile specimen, such as a plastic container during a drawingoperation, goes through a minimum value of some relatively low value ofstrain rate i.e., the velocity at which a specimen is being straineddivided by the original length of specimen being strained. It has beenfound in accordance with this invention that the provision of aplurality of closely spaced relieved areas in the form of elongatedparallel, shallow grooves in the periphery of a die center pad of a dieassembly prevents undesired elongation during a drawing or a redrawingoperation and prevents the above-noted conventional thinning or neckingof container bodies during conventional drawing methods performed byconventional die apparatuses, and produces containers of a generallyuniform wall thickness and strength, and high esthetic characteristics.

It is, therefore, an object of this invention to provide a novel drawnplastic article including a generally cupshaped body having interior andexterior peripheral surfaces, means forrning integral portions of onlyone of the peripheral surfaces for preventing the necking down of thebody during the drawing thereof whereby the body is of a generallyuniform wall thickness and the integral portions are of a size which aregenerally indiscernible to the naked eye and insufficient to materiallydisfigure the body.

A further object of this invention is to provide a novel drawn plasticarticle comprising a generally cup-shaped body having interior andexterior peripheral surfaces, one of the peripheral surfaces beingsmooth and unbroken, and the other of the peripheral surfaces having aplurality of parallel ribs ranging in height upwardly from about .0005inch to a height suficient to prevent necking down but insufiicient tomaterially disfigure the drawn article.

Still another object of this invention is to provide a novel drawnplastic article of the type described in which the number of ribs rangebetween five to one-hundred ten for each inch of periphery of thecup-shaped body.

With the above and other objects in view that will hereinafter appear, te nature of the invention will be more clearly understood by referenceto the following detailed description, the appended claims and theseveral views illustrated in the accompanying drawings.

FIGURE 1 is an axial sectional view through a redrawn plastic cup-shapedarticle, and illustrates the generally uniform wall thickness of thearticle and numerous raised areas or ribs formed in the internal surfacethereof, the size of the ribs being highly exaggerated.

FIGURE 2 is a highly enlarged fragmentary sectional view taken alongline 2-2 of FIGURE 1 and more clearly illustrates the plurality ofraised areas in the interior surface of the article.

FIGURE 3 is a highly enlarged fragmentary transverse sectional viewtaken through another article of this invention on a line substantiallyidentical to the line 22 of FIGURE 1, and illustrates a plurality ofclosely spaced parallel generally U-shaped areas or ribs in an interiorperipheral surface of the article.

A novel cup-shaped article or container formed by the redrawing processheretofore described is generally designated by the reference numeral10. The drawn or redrawn container 10 comprises a container body 11defined between an exterior peripheral surface 12 and an interiorperipheral surface 13. The body or wall 11 tapers slightly upwardly froma bottom wall 14 toward an upper end portion (unnumbered) terminating ata radially outwardly directed flange 15.

The inner peripheral surface 13 of the body 11 is provided with aplurality of identical elongated closely spaced raised areas or ribs 16(FIGURE 2). The raised ribs extend from a radius portion 17 joining thebottom wall 14 to the body wall 11 and terminate at a radius portion 18joining the wall 10 to the radially outwardly directed flange 15.

Each of the ribs 16 is substantially V-shaped in transverse section(FIGURE 2) and converging wall surfaces 20, 21 thereof enclose an angleof approximately ninety degrees. The height of each of the ribs 16 isapproximately 0.0005 inch and the number of the ribs varies inaccordance with the diameter and circumference of the body wall 11.There are preferably approximately between five to one-hundred ten ribs16 for each inch of periphery or circumference of the body wall 11.While this number of ribs per each inch of circumference is preferred,the maximum number of ribs is limited only by the maximum number ofgrooves which can be accurately machined or formed in a die center pad,as described, in the commonly assigned application heretofore noted. Theminimum number of ribs per each inch of circuference is similarlylimited only by the minimum number of ribs necessary to achieve theobject of this invention, and five such ribs in each inch ofcircumference have been found satisfactory to preclude the formation ofa neck of thin material adjacent the bottom wall 14 and maintain thethickness of the body wall 11 substantially uniform thoughout. While theribs 16 are quite numerous, they are of a height which is generallyinsufficient to materially disfigure the container 10 and aresubstantially undiscernible to the naked eye.

Working embodiments of the container 10 have been manufactured andtested, and one such container was formed by employing a die center padhaving a length of approximately five and one-half inches, a diameter of1.8410 inches and a circumference of approximately 5.786 inches. Thebody of the die center pad was provided with 720 V-shaped groovesarranged in parallel relationship to each other and to the axis of thedie center pad. Each of the grooves was approximately four inches inlength and adjacent grooves were spaced from each other acenter-to-center distance of approximately .00803 inch or approximatelyone-half degree of are between adjacent grooves or approximately 107.2grooves per each inch of circumference of the body. The converging wallportions defining each of the grooves set off an angle of approximatelyninety degrees and the depth of each groove was 0.0005 inch. The maximumwidth of the grooves was 0.001 inch. The working embodiment of thecontainer 10 was, of course, provided with ribs corresponding to thesize, shape and number of grooves of the die center pad.

Many containers were redrawn from polycarbonate material having anominal 0.012 inch thickness which previously could not be drawn becausethe container body and/or bottom always tore and/or thinned or neckeddown markedly. Further containers were drawn fromacrylonitrile-butadiene-styrene tel-polymer.

Referring to FIGURE 3 of the drawing, another cupshaped article orcontainer constructed in accordance with this invention is referred toby the reference numeral 30 and comprises a generally cylindrical body31 having an exterior peripheral surface 32 and an interior peripheralsurface 33. The container 30 is substantially identical to the container10 and includes a bottom wall 34 and a flange (not shown) correspondingto the flange 15 of the container 10.

The interior peripheral surface 33 on the body 31 is provided with aplurality of closely spaced parallel raised areas or ribs 36. Each ofthe ribs 36 is substantially U- shaped in transverse section and isapproximately 0.0005 inch in height. The container 30 preferablyincludes one such rib for each ten degrees of arc of the body 31, andthe maximum width of each of the U-shaped ribs is approximately 0.010inch.

Containers corresponding to the containers 30 have been drawn in themanner disclosed in the above-noted application by employing a diecenter pad having a body of approximately five and one-half inches inlength. Thirty-six identical U-shaped grooves were formed in theexterior peripheral surface of the die center pad body with each groovebeing approximately four inches long. The diameter of the body was 2.041inches with a circumference of approximately 6.408 inches. The U-shapedgrooves were spaced apart a center-to-center distance of ten degrees ofare or approximately 5.62 grooves in each inch of circumference of thebody. The depth of each groove was approximately 0.0005 inch and thewidth of each groove was 0.010 inch. The drawn containers includecorrespondingly sized and shaped ribs.

It will be apparent from the foregoing that there has been providedvarious forms of a novel cold-drawn plastic container wherein aplurality of closely spaced ribs in an interior surface thereof preventsthe formation of a neck of thin material in the container wall justslightly removed from the radius portion which joins the body wall tothe bottom wall thereof. While this problem of thinning or necking hasbeen solved by the provision of a plurality of such ribs, other ribconfigurations are considered to be within the scope of this invention.For example, serpentine or spiral-like ribs might also be formed in theinterior surface of the container body by forming corresponding ribs inthe exterior surface of a die center pad.

Thus, while preferred forms and arrangements have been shown toillustrate this invention, it is to be understood that various changesin details and arrangements may be made without departing from thespirit and scope of the invention as defined in the appended claims.

I claim:

1. A cold-drawn plastic container comprising a body wall terminating ina bottom wall, said body wall including an interior peripheral surfaceand an exterior peripheral surface, a plurality of closely spacedelongated raised areas extending substantially the length of said bodywall upon the interior peripheral surface thereof, and each of saidraised portions being of a height which is insufficient to materiallydisfigure the container and being generally undiscernible to the nakedeye.

2. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, means forming integralportions of said body for preventing the necking down of said bodyduring the drawing thereof whereby said body is of a generally uniformwall thickness, and said means being generally insufiicient tomaterially disfigure the body and being generally indiscernible to thenaked eye.

3. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, means forming integralportions of only one of said peripheral surfaces for preventing thenecking-down of said body during the drawing thereof whereby said bodyis of a generally uniform wall thickness, and the other of saidperipheral surfaces being absolutely smooth and unbroken.

4. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, said body having an upperperipheral end portion and a bottom wall portion, means forming integralportions of one of said peripheral surfaces for preventing thenecking-down of said body during the drawing thereof whereby said bodyis of a generally uniform wall thickness and is devoid of a necked-downportion adjacent the bottom wall portion thereof, said means extendingfrom the peripheral end portion of said body to the bottom wall poritonthereof, and said integral portions being a plurality of ribs whichgradually merge into a smooth continuous unbroken surface adjacent saidbottom wall portion.

5. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, said body having an upperperipheral end portion and a bottom wall portion, means forming integralportions of only one of said peripheral surfaces for preventing thenecking-down of said body during the drawing thereof whereby said bodyis of a generally uniform wall thickness and is devoid of a necked-downportion adjacent the bottom wall portion thcreof, said means extendingfrom the peripheral end portion of said body to the bottom wall portionthereof, and said integral portions being a plurality of ribs whichgradually merge into a smooth continuous unbroken surface adjacent saidbottom wall portion.

6. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, one of said peripheralsurfaces being smooth and unbroken, a plurality of elongated raised ribsin the other of said peripheral surfaces, each of said raised ribsranging in height upwardly from about .0005 inch to a height sufficientto prevent necking-down but insufficient to materially disfigure thedrawn article.

7. A drawn plastic article comprising a generally cylindrical cup-shapedbody having interior and exterior peripheral surfaces, one of saidperipheral surfaces including a plurality of means for preventing theneckingdown of said article during the drawing thereof, and said meansranging in number between five to one-hundred ten for each inch ofcircumference of said cylindrical body wall.

8. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, said body being of agenerally uniform thickness, said body having a body wall defined bysaid interior and exterior peripheral surfaces, said body wall havingupper and lower end portions, said exterior peripheral surface beingabsolutely smooth and unbroken, a plurality of means forming integralportions of said interior peripheral surface for preventing the neckingdown of said body during the drawing thereof, said means beinginsufficient to materially disfigure the interior peripheral surfaces ofthe body and being generally indiscernible to the naked eye, saidplurality of means being a plurality of parallel ribs extending betweensaid upper and lower end portions, and each of said ribs ranging inheight upwardly from .0005 inch.

9. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, said body being of agenerally uniform thickness, said body having a body wall defined bysaid interior and exterior peripheral surfaces, said body wall havingupper and lower end portions, said exterior peripheral surface beingabsolutely smooth and unbroken, a plurality of means forming integralportions of said interior peripheral surface for preventing the neckingdown of said body during the drawing thereof, said means beinginsufiicient to materially disfigure the interior peripheral surfaces ofthe body and being generally indiscernible to the naked eye, saidplurality of means being a plurality of parallel ribs extending betweensaid upper and lower end portions, and said ribs ranging in numberbetween five to 6 one-hundred ten for each inch of periphery of saidbody wall.

10. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, said body being of agenerally uniform thickness, said body having a body Wall defined bysaid interior and exterior peripheral surfaces, said body wall havingupper and lower end portions, said exterior peripheral surface beingabsolutely smooth and unbroken, a plurality of means forming integralportions of said interior peripheral surface for preventing the neckingdown of said body during the drawing thereof, said means beinginsufiicient to materially disfigure the interior peripheral surfaces ofthe body and being generally indiscernible to the naked eye, saidplurality of means being a plurality of parallel ribs extending betweensaid upper and lower end portions, and each of said ribs ranging inheight upwardly from .0005 inch, and said ribs ranging in number betweenfive to one-hundred ten for each inch of periphery of said body wall.

11. The drawn plastic article as defined in claim 8 wherein said ribsare of a generally V-shaped cross-sectional configuration.

12. The drawn plastic article as defined in claim 10 wherein said ribsare of a generally V-shaped cross-sectional configuration.

13. A drawn plastic article comprising a generally cupshaped body havinginterior and exterior peripheral surfaces, said body being of agenerally uniform thickness, said body having a body wall defined bysaid interior and exterior peripheral surfaces, said body wall havingupper and lower end portions, said exterior peripheral surface beingabsolutely smooth and unbroken, a plurality of means forming integralportions of said interior peripheral surface for preventing the neckingdown of said body during the drawing thereof, said means beinginsufficient to materially disfigure the interior peripheral surface ofthe body and being generally indiscernible to the naked eye, and saidplurality of means being a plurality of parallel ribs extending betweensaid upper and lower end portions.

14. The drawn plastic article as defined in claim 13 wherein said ribsgradually merge into a smooth continuous unbroken surface adjacent saidlower end portion.

References Cited UNITED STATES PATENTS Re. 25,618 7/1964 Goodman 2291.53,169,688 2/1965 Schad 229-1.5 3,194,468 7/1965 Baron 2291.5

DAVID M. BOCKENEK, Primary Examiner.

